Internalin B promotes the replication of Listeria monocytogenes in mouse hepatocytes

The uptake of Listeria monocytogenes by a variety of cell types in vitro is facilitated by the protein products of the inlAB (internalin) operon expressed by the organism. In the case of mouse hepatocytes, the extent to which inlAB expression influenced the uptake of Listeria in vitro was markedly dependent upon the ratio of bacteria to cells. At a ratio of 100:1, greater than 40-fold fewer transposon-induced inl4B mutant listeriae entered hepatocytes compared to the isogenic wild-type control; the difference was only fourfold, however, in cultures inoculated at a 1:1 ratio. Similarly, the uptake of in-frame inlB or inlAB deletion mutants differed only fourfold from the uptake of wild-type or inlA mutant Listeria at a 1:1 multiplicity of infection. Mutations affecting inlB or inlAB, on the other hand, resulted in a marked decrease in the capacity of Listeria to proliferate within mouse hepatocytes in vivo and in vitro. Electron micrographs of Listeria-infected hepatocytes demonstrated the impaired capacity of inlB mutants to escape from endocytic vacuoles and to enter the cytoplasm where proliferation occurs. These findings indicate that the protein product of inlB exerts a significant effect on the intracellular replication of Listeria.     

Adrenaline enhances LPS-induced IL-10 synthesis: evidence for protein kinase A-mediated pathway

The aim of the present study was to investigate the role of cAMP in enhanced IL-10 synthesis in human mononuclear cells. Adrenaline is known to act via the alpha- and beta-adrenergic receptors which are coupled to adenylyl cyclase. The effects of cAMP elevation on IL-10 synthesis were studied at the protein level by ELISA and at the level of mRNA by RT/PCR. In this in vitro model adrenaline enhanced the LPS-induced synthesis of IL-10 with parallel suppression of TNF synthesis. These effects were demonstrated both at the protein level and the level of mRNA. To analyze the role of cAMP we antagonized this effect by application of (Rp)-cAMPS, a diastereomer of adenosine-3',5'-cyclic phosphorothioate, known to inhibit competitively the cAMP-induced activation of protein kinase A. Simultaneous addition of adrenaline and (Rp)-cAMPS led to a reversal of IL-10 synthesis to values induced by LPS stimulation alone. The kinetic analysis in LPS-stimulated mononuclear cells revealed a significant delay of IL-10 synthesis starting after 7 h compared with TNF synthesis which showed the first significant increase at 90 min. Finally, the combination of adrenaline and exogenous IL-10 led to a more pronounced suppression of TNF synthesis after LPS stimulation compared to suppression by IL-10 or adrenaline alone. The present results suggest the role of protein kinase A activation for adrenaline-induced IL-10 synthesis in human mononuclear cells. Additionally, based on the kinetic analysis and further experiments described in the literature, endogenous IL-10 could contribute to the adrenaline-induced suppression of TNF synthesis after prolonged incubation. These in vitro results could explain the suppression of TNF plasma concentration after parallel infusion of LPS and epinephrine compared to LPS infusion alone as has been demonstrated in a first human study.     

Something Old,Something New: Integrating Engineering Practice into the Teaching of Engineering Mechanics

This paper presents a multifaceted method for teaching engineering mechanics designed to satisfy the following set of desiderata: (1) integrate engineering practice into the teaching of engineering science; (2) address a wide set of learning styles; (3) provide opportunities for practice in group work and learning; (4) promote communication and synthesizing skills; (5) engage students in the teaching and learning process; (6) maintain traditional achievement levels with respect to traditional measures; (7) motivate students to continue their engineering studies; and (8) maintain reasonable resource demands. Consistent with this variety of objectives, the approach presented here is composed of a variety of ingredients. In addition to the standard homework problems and exams, these ingredients include design projects, group work, basic competency exams, computational environments for simulating and visualizing phenomena, multimedia instructional tools, hands-on experiences, and student presentations. This educational model is intended to be suitable for teaching engineering mechanics in general, but this paper focuses on a particular sophomore-level mechanics of materials course in which the method has been implemented, refined over several years of classroom use, and tested relative to traditional approaches. The paper describes the and techniques that together make up the method, followed by summaries of the results of evaluations that have been applied to the course.     

Monitoring children’s developmental progress using augmented toys and activity recognition

Previous research has established the connection between the way in which children interact with objects and the potential early identification of children with autism. Those findings motivate our own work to develop "smart toys," objects embedded with wireless sensors that are safe and enjoyable for very small children, that allow detailed interaction data to be easily recorded. These sensor-enabled toys provide opportunities for autism research by reducing the effort required to collect and analyze a child’s interactions with objects. In the future, such toys may be a useful part of clinical and in-home assessment tools. In this paper, we discuss the design of a collection of smart toys that can be used to automatically characterize the way in which a child is playing. We use statistical models to provide objective, quantitative measures of object play interactions. We also developed a tool to view rich forms of annotated play data for later analysis. We report the results of recognition experiments on more than fifty play sessions conducted with adults and children as well as discuss the opportunities for using this approach to support video annotation and other applications.     

Subcellular Localisation of a Quinoline-Containing Fluorescent Cyclometallated IrIII Complex in Plasmodium falciparum

A fluorescent analogue of a previously synthesised N,N-chelated Ir^III complex was prepared by coordination of the organic ligand to an extrinsic bis(2-phenylpyridine)iridium(III) fluorophore. This cyclometallated Ir^III complex in itself displays good, micromolar activity against the chloroquine-sensitive NF54 strain of Plasmodium falciparum. Live-cell confocal microscopy found negligible localisation of the fluorescent complex within the digestive vacuole of the parasite. This eliminated the haem detoxification pathway as a potential mechanism of action. Similarly, no localisation of the complex within the parasitic nucleus was found, thus suggesting that this complex probably does not interfere with the DNA replication process. A substantial saturation of fluorescence from the complex was found near phospholipid structures such as the plasma and nuclear membranes but not in neutral lipid bodies. This indicates that an association with these membranes, or organelles such as the endoplasmic reticulum or branched mitochondrion, could be essential to the efficacies of these types of antimalarial compounds.     

Processing,microstructure, and mechanical properties of hot-pressed ZrB2 ceramics with a complex Zr/Si/O-based additive

Densification behavior, microstructure, and mechanical properties of zirconium diboride (ZrB₂) ceramics modified with a complex Zr/Si/O-based additive were studied. ZrB₂ ceramics with 5–20 vol.% additions of Zr/Si/O-based additive were densified to >95% relative density at temperatures as low as 1400°C by hot-pressing. Improved densification behavior of ZrB₂ was observed with increasing additive content. The most effective additive amount for densification was 20 vol.%, hot-pressed at 1400°C (∼98% relative density). Microstructural analysis revealed up to 7 vol.% of residual second phases in the final ceramics. Improved densification behavior was attributed to ductility of the silicide phase, liquid phase formation at the hot-pressing temperatures, silicon wetting of ZrB₂ particles, and reactions of surface oxides. Room temperature strength ranged from 390 to 750 MPa and elastic modulus ranged from 440 to 490 GPa. Vickers hardness ranged from 15 to 16 GPa, and indentation fracture toughness was between 4.0 and 4.3 MPa·m^1/2. The most effective additive amount was 7.5 vol.%, which resulted in high relative density after hot-pressing at 1600°C and the best combination of mechanical properties.